The correct answer would be option A: "The beauty of nature amid war". In the excerpt, the author mentions several traits of nature, emphasizing the beauty of the larks singing and then mentions "amid the guns below" so one could infer that there is a war going on.
Option B is incorrect because the author does not mention anything that could point to the scene being a graveyard. Option C is incorrect because the larks (on their own) are not the theme, they are merely a topic and option D is incorrect because the author does not mention anything about the war, except for the use of guns (resolving differences or not).